The present invention relates to a watch type paging receiver and, more particularly, to a receiver using an air cell or so called air-zinc cell of non-returnable type for the battery.
Depending on the development and popularization of a paging receiver or so called "pocket bell" in recent year, minimization of a receiver of this kind has been promoted every year. For the receiver of this kind, as a form of a user interface, various kinds of new types such as from a conventional match box type up to a pencil type, a card type and a watch type have been introduced one after another into the market. One with the box type has substantially the same structure as the general watches, however, the essentially different point thereof from the other is to require a relatively larger battery capacity for driving a receiver circuit and yet extremely many times of replacements of the batteries.
An example of combination of a solar cell and a secondary battery is disclosed in U.S. Pat. No. 5,007,105 as a watch type paging receiver where a difficulty in charging by removing the secondary battery has been eliminated, notwithstanding a drawback still remains in higher cost, heavy weight and the like due to the increase of the number of components.
Hitherto, as a battery for a watch type paging receiver, a lithium cell or a nickel cadmium cell have been utilized despite of the limited capacity of the battery. Accordingly, the battery need to be replaced relatively in frequent. This requires a structure of the receiver for easy replacement of the battery, and in general a rear cover to be provided on a body casing of the receiver is made releasable and thus such structure that the battery is replacable by moving the rear cover has been employed.
On the other hand, in order to secure a waterproof arrangements within a receiver, various kinds of waterproof structures are adopted so as to prevent deterioration of a waterproof characteristic even when the rear cover is released.
Recently, the development of the air cell or air-zinc cell has been promoted, and presently one with a relatively larger capacity may thus be obtained. Even in the card type paging receiver or the watch type paging receiver as hereinbefore described, the air cell is intended to be used instead of the conventional lithium cell and nickel cadmium cell.
As an air cell of this kind, there has been introduced a coin type air cell of PR 2330 manufactured by Matsushita Denti Industrial Co., Ltd., which coin type air cell is commercially available with compact feature, light weight, and larger electric capacity and is optimum to the paging receiver.
In an air cell of this kind, however, air supply is needed for generating an electric power which in turn requires to secure air permeability for communicating between the battery and the outside of the body when the battery is accommodated inside the body. In this case, the air cell may not be advantageously available to the conventional watch type receiver. Namely, the watch type receiver requires the waterproof characteristic at the extent where no difficulty arises in the daily life and in particular it provides a closure construction for the rear cover so as to eliminate a problem due to sweating or the like from a human body when it is applied to the person's wrist. Therefore, when the air cell modification is used for the watch type receiver provided with such a counter measure of waterproof, the air supply comes impossible and thus an operation of the air cell is stopped.